Wide angle lens and wide angle camera comprising same

ABSTRACT

A wide-angle lens for condensing light from a subject, wherein the wide-angle lens is a convex lens having all types of continuous focuses generated by tracing a line segment with respect to one axis and then rotating the line segment with respect to the axis. The wide-angle camera includes a lens for condensing light from a subject; and an image sensor, disposed at a focal length of the lens, for outputting, as electrical signals, an image generated by the light which has passed through the lens, wherein the lens is a convex lens having all types of continuous focuses generated by tracing a line segment with respect to one axis and then rotating the line segment with respect to the axis, and the image sensor is formed to have a curved surface so as to correspond to the focal length of the lens.

TECHNICAL FIELD

The present disclosure relates to a wide view angle lens which isapplicable to a Closed-Circuit TV (CCTV) camera or the like, and a wideview angle camera including the lens and, more particularly, to a lensand a camera capable of obtaining a distortion-free wide view angleimage without performing software processing.

BACKGROUND ART

In general, a camera is a device that condenses light, reflected from asubject, through a lens so as to fix an image at a specific position.Recently, digital cameras, in which a film in the structure of the firstcamera is replaced with a digital image sensor, have been widely used.Referring to FIG. 1, the structure of a general digital camera can beeasily understood.

Meanwhile, it is desirable that a CCTV camera used for security canmonitor a wide area using one camera. In order to achieve such apurpose, a camera used for monitoring may employ a wide-angle lens suchas a fisheye lens. However, an image obtained through a fisheye lens hasproblem in that it is severely distorted. Meanwhile, another example ofa camera structure for achieving the purpose of wide view anglephotographing is disclosed in Korean Laid-Open Patent Publication No.2013-0037883.

The laid-open patent adopts a structure in which a wide range of lightcan be condensed into a camera using a reflection structure on a cameralens so that a wide range can be photographed. Such a conventional wideview angle camera has an advantage in that it can photograph a widerange, but has a problem in that a photographed image is distorted, as afatal disadvantage. Therefore, since it is necessary to add an imageprocessing module for correcting an image distorted as described above,the camera is structurally complicated, and image processing time isrequired, which causes delay in the photographing time and the finalimage output time. In addition, since the image processing module isadded, the manufacturing cost of the camera increases.

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

The present disclosure has been made in order to solve the problemsdescribed above, and an objective of the present disclosure is toprovide a wide view angle lens and a wide view angle camera, in whichthe structure of the wide view angle lens is improved such that aphotographed image is not distorted and wide view angle photographing isenabled.

Technical Solution

In order to achieve the above-described objective, a wide view anglelens according to an embodiment of the present disclosure is a wide viewangle lens configured to condense light from a subject.

The lens is a convex lens having all types of continuous focal pointsformed by drawing a line segment with respect to one axis and rotatingthe line segment with respect to the axis.

Advantageous Effects

The wide view angle lens according to the present disclosure isconfigured such that a focused image is formed on a curved face, and awide view angle camera including the lens is provided with an imagesensor corresponding to a curved face of the image formed by the lens.Accordingly, there is provided an effect of providing a camera capableof implementing wide view angle photographing in an innovative manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a principle of a general digital camera;

FIG. 2 is a view showing a principle in which a cylinder lens forms animage;

FIG. 3 is a view showing an example of an arrangement of a lens and animage sensor in a camera according to a first embodiment of the presentdisclosure;

FIG. 4 is a view seen in a “Z” direction shown in FIG. 3;

FIG. 5 is a sectional view taken along line V-V in FIG. 3;

FIG. 6 is a view showing a modified structure of the first embodiment;

FIG. 7 is a view showing an arrangement of an image sensor in a camerastructure according to a second embodiment of the present disclosure;

FIG. 8 is a plan view of the camera structure shown in FIG. 7;

FIG. 9 is a view showing an arrangement of an image sensor in a camerastructure according to a third embodiment of the present disclosure; and

FIG. 10 is a view showing a modified structure of the third embodiment.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings.

FIG. 3 is a view showing an example of an arrangement of a lens and animage sensor in a camera according to a first embodiment of the presentdisclosure. FIG. 4 is a view seen in a “Z” direction shown in FIG. 3.FIG. 5 is a sectional view taken along line V-V in FIG. 3. FIG. 6 is aview showing a modified structure of the first embodiment. FIG. 7 is aview showing an arrangement of an image sensor in a camera structureaccording to a second embodiment of the present disclosure. FIG. 8 is aplan view of the camera structure shown in FIG. 7. FIG. 9 is a viewshowing an arrangement of an image sensor in a camera structureaccording to a third embodiment of the present disclosure. FIG. 10 is aview showing a modified structure of the third embodiment.

In the figures, a virtual line arrow indicates a direction in whichlight passes through a lens and enters an image sensor.

Hereinafter, the structure and effects of the lens will be described inthe course of describing the structure and effects of a wide view anglecamera including a wide view angle lens according to the presentdisclosure.

Referring to FIGS. 3 to 10, a camera capable of photographing in a wideview angle according to embodiments of the present disclosure includes alens 20 and an image sensor 30.

The lens 20 is a component that serves to condense light reflected froma subject 100. The lens 20 used in the present disclosure is obtained byprocessing a rod-shaped convex lens again. An example of a rod-shapedconvex lens includes a cylinder lens. In general, a cylinder lens is alens of a type in which X axis and Y axis radii are different from eachother. The cylinder lens 200 is formed in a semi-cylindrical shape, forexample, as shown in FIG. 2. Meanwhile, the cylinder lens 200 may bemanufactured in a cylindrical shape. The cylinder lens forms a focusedimage along one line rather than forming a focused image based on asingle point. Generally, since the cylinder lens has a curved face onlyin one axial direction and does not have a curved face in another axialdirection, light is condensed only in the one axial direction.Therefore, the cylinder lens 200 shown in FIG. 2 forms a linear image inthe Y-axis direction. The principle in which the light reflected from asubject 100 passes through the cylinder lens and forms an image on theimage sensor 30 can be easily understood with reference to FIG. 2.Referring to FIG. 2, an image of the subject 100 is symmetricallychanged in the left-right direction X when passing through the cylinderlens, and then passing through a diaphragm 40 so as to be formed in theimage sensor 30. Meanwhile, when the image of the subject 100, which haspassed through the cylinder lens, is formed on the image sensor 30, theimage of the subject 100 is not symmetrically changed in thelongitudinal direction Y.

In the present disclosure, such a rod-shaped convex lens is processed tobe bent once again such that curved faces are formed in both the X andY-axis directions, so that an undistorted image can be formed so as tobe focused and a reduced image for a large object can be formed in thecamera. That is, the lens 20 is processed such that the trace of thefocal distance D forming the focused image is formed in a curve.Accordingly, the lens 20 forms a structure bent with a curvature equalto the curvature of the curve formed by the trace of the focal distanceD. In the present disclosure, the lens 20 is a constituent elementacting as a pinhole in principle of a camera. In particular, while aconventional lens forms an image at one focal point, the lens 20employed in the present disclosure is characterized in that it isconfigured to form an image on a curve. That is, in the presentdisclosure, the lens 20 functions like a slit-shaped pinhole in thecamera principle. Therefore, the lens 20 functions to form a wide viewangle image without distortion at the focal length D formed on thecurve. That is, the lens 20 simultaneously performs the role of aslit-shaped pinhole and the unique role as a lens for condensing light.

In addition, since the lens 20 has a structure bent with a constantcurvature in the Y direction, there is a spherical center 25 accordingto the curvature of the lens 20 in the Y direction. When the imagesensor 30, which will be described later, is positioned in front of thespherical center 25 with respect to the center of the lens 20, an imagein the Y direction does not change symmetrically with the actual object.Meanwhile, when the image sensor 30 is positioned behind the sphericalcenter 25 as shown in FIGS. 6 and 10, an image in the Y directionchanges symmetrically with the actual object.

For example, the lens 20 may be a convex lens having all the types ofcontinuous focuses that are generated by drawing a line segment withrespect to an imaginary axis in space and rotating the line segment withrespect to the axis. The line segment may be a straight line or a partof a curve.

The focal length D defined in the present disclosure means a trace of aposition in which a subject in the depth of field of the lens isfocused. Therefore, the focal length D has the value of a distancebetween the lens 20 and the spherical center 25 minus a or a distancebetween the lens 20 and the spherical center 25 plus a.

Also, since the lens 20 has a structure bent with a constant curvaturein the Y direction, the size of the image formed on the image sensor 30may be smaller than the size of the actual object.

The image sensor 30 is arranged to correspond to the focal length D ofthe lens 20. The image sensor 30 outputs a clear image formed by lightpassing through the lens 20 as an electric signal. The electric signalof the image sensor 30 may be current or voltage. As the image sensor30, a CCD sensor or a CMOS sensor may be employed. The image sensor 30is formed to have a curved face to correspond to the focal length D ofthe lens 20. The image sensor 30 may be formed by attaching an imagesensor having a fine size onto a curved member. Meanwhile, the imagesensor 30 may be directly laminated on a CCD or CMOS circuit by applyinga continuous semiconductor manufacturing process to the surface of acurved member. A manufacturing process of the image sensor 30 may beconfigured by applying a known semiconductor manufacturing process.

As described above, since the structure corresponding to the focaldistance D of the lens 20 is configured to be formed in a curved shapeand the image sensor 30 is configured in a curved shape corresponding aface corresponding to the focal distance D of the lens 20, an imageformed on the image sensor 30 is not distorted compared with the actualimage. Further, the lens 20 is processed to be bent into a curved shape,thereby widening the area where light is condensed on the lens 20, whichenables wide view angle photographing.

A shutter film (not shown) may be disposed between the lens 20 and theimage sensor 30. As the shutter film, a known shutter film structure maybe employed. The shutter film may have a flat or curved shape.

A diaphragm (or iris or iris diaphragm) 40 may be disposed between thelens 20 and the image sensor 30. The diaphragm 40 functions to adjustthe amount of light passing through the lens 20. The diaphragm 40 mayemploy a known iris structure of a camera. Meanwhile, the diaphragm 40may be disposed in front of the lens 20.

The lens 20, the image sensor 30, the shutter film, and the diaphragm 40may be disposed inside a frame (not shown) so as to form a camera.

Cameras according to the first embodiment, which are shown in FIGS. 3 to5, include a lens 20 obtained by processing a rod-like convex lens to bebent with the same curvature with respect to one axis. The one axismeans an imaginary axis, for example, a virtual axis passing verticallythrough the paper plane at the spherical center 25 in FIG. 4. Morespecifically, the camera is configured such that the lens 20 is bent tohave a constant curvature in the Y direction. Further, the image sensor30 is disposed in front of the spherical center 25 generated by thecurvature of the lens 20 in the Y direction. Accordingly, an imageformed on the image sensor 30 forms an image of the same shape as theactual object in the Y direction. The lens 20 may be processed to havean angle of view θ of, for example, about 120° so as to be suitable foran angle to be photographed. That is, the lens 20 may be obtained byforming a rod-shaped convex lens in the shape of a part of a cylindricalshape with respect to one axis.

Meanwhile, in a modified structure of the first embodiment shown in FIG.6, the image sensor 30 is arranged behind the spherical center 25generated by the Y-directional curvature of the lens 20. Accordingly, inthe structure shown in FIG. 6, an image formed on the image sensor 30 isformed in a symmetrical shape in the Y direction with respect to theactual object thereof.

Meanwhile, the lens 20 constituting the camera according to a secondembodiment shown in FIGS. 7 and 8 may be processed in a cylindricalstructure so as to photograph an angle of view of 360° with respect toone axis. In this case, the structure of the image sensor 30 is alsoformed in a cylindrical structure like the lens 20. That is, the lens 20may have a rod-shaped convex lens having a cylindrical structure withrespect to one axis.

Meanwhile, a lens 20 constituting a camera according to a thirdembodiment shown in FIG. 9 may be processed into a truncated conicalstructure with respect to one axis. In this case, the structure of theimage sensor 30 is also formed into a truncated conical structure likethe lens 20. When the lens 20 is processed into the truncated conicalstructure shown in FIG. 9, the angle of view θ of the lens 20 can befurther widened. In particular, a camera structure similar to that ofthe third embodiment shown in FIG. 9 is suitable for a CCTV camerainstalled on the ceiling of a building.

Meanwhile, the camera shown in FIG. 10 has a modified structure of thecamera shown in FIG. 9. That is, the image sensor 30 is disposed behindthe spherical center 25 generated by the Y-directional curvature of thelens 20. Accordingly, in the structure shown in FIG. 10, an image formedon the image sensor 30 is formed in a symmetrical shape in the Ydirection with respect to the actual object thereof. Thus, the lens 20may be manufactured in a truncated conical structure or a structurecorresponding to a part of the truncated conical structure with respectto one axis using a rod-shaped convex lens.

Hereinafter, acting effects of a wide view angle lens including theabove-described components and a wide view angle camera including thelens will be described in detail.

First, the subject 100 reflects light from a light source such assunlight or a lamp. The light reflected from the subject 100 passesthrough the lens 20. Since the lens 20 is bent with respect to one axis,a focused image is formed on a curved face. Since the image sensor 30 isdisposed on a curved face corresponding to the focal length D of thelens 20, an image formed through the lens 20 is formed on the imagesensor 30 without being distorted. The image sensor 30 outputs theformed image signal as an electric signal. The electric signal outputfrom the image sensor 30 is converted into a form of an image visible toa human in an image processing module and the image is output to amonitor or a recording medium. That is, an essential feature of thepresent disclosure is that an image focused by the lens 20 is formed ona curved face, and the image sensor 30 is disposed at a positioncorresponding to the curved face, so that a distortion-free image can beobtained. In addition, the lens 20 has an advantage in that it can bebent and processed into a face curved as much as necessary, so that itis possible to very easily implement required wide view anglephotographing.

As described above, according to a camera structure of the presentdisclosure, a structure corresponding to a focal length of a lensforming an image is formed on a curved face, and an image sensorcorresponding to the curved face is provided. Accordingly, there isprovided an effect of providing a camera capable of implementing wideview angle photographing in an innovative manner.

In addition, the camera structure according to the present disclosure iscapable of obtaining a wide-angle image that is not distorted even whena lens group, which is constituted with a plurality of conventional lenshaving a complicated structure, is not employed by processing arod-shaped convex lens into a curved face with respect to one axis.Thus, it is possible to reduce the manufacturing cost of a camera,thereby providing a very advantageous effect to manufacturers andconsumers in terms of economy.

While the present disclosure has been described with reference toembodiments, it is to be understood that the present disclosure is notto be limited by such embodiments, and various changes and modificationsmay be made without departing from the technical idea of the presentdisclosure.

MODE FOR CARRYING OUT THE INVENTION

In order to achieve the above-described objective, a wide view anglelens according to an embodiment of the present disclosure is a wide viewangle lens configured to condense light from a subject.

The lens is a convex lens having all types of continuous focal pointsformed by drawing a line segment with respect to one axis and rotatingthe line segment with respect to the axis.

Meanwhile, in order to achieve the above-described objective, a wideview angle lens according to an embodiment of the present disclosureincludes a lens configured to condense light from a subject, and animage sensor disposed at a focal length of the lens and configured tooutput an image of light passing through the lens as an electric signal.

The lens is a convex lens having all types of continuous focal pointsformed by drawing a line segment with respect to one axis and rotatingthe line segment with respect to the axis, and the image sensor isformed in a curved shape so as to correspond to the focal length of thelens.

The lens may be manufactured by bending a rod-shaped convex lens intoany one of a cylindrical shape, a part of the cylindrical shape, atruncated conical shape, and a part of the truncated conical shape withrespect to one axis.

1. A wide view angle lens for condensing light from a subject, whereinthe lens is a convex lens having all types of continuous focal pointsformed by drawing a line segment with respect to one axis and rotatingthe line segment with respect to the axis, wherein the lens is processedin such a manner that a rod-shaped convex lens is processed again to bebent again such that a trace of a focal length forming a focused imageis formed as a curve, and wherein the lens forms a structure bent with asame curvature as a curvature of the curve formed by the trace of thefocal length.
 2. A wide view angle camera comprising: a lens configuredto condense light from a subject; and an image sensor disposed at afocal length of the lens and configured to output an image of lightpassing through the lens as an electric signal, wherein the lens is aconvex lens having all types of continuous focal points formed bydrawing a line segment with respect to one axis and rotating the linesegment with respect to the axis, wherein the lens is processed in sucha manner that a rod-shaped convex lens is processed again to be bentagain such that a trace of a focal length forming a focused image isformed as a curve, wherein the lens forms a structure bent with a samecurvature as a curvature of the curve formed by the trace of the focallength, and wherein the image sensor is formed in a curved shape so asto correspond to the focal length of the lens.
 3. The wide view anglecamera of claim 2, wherein the lens is manufactured by bending arod-shaped convex lens into any one of a cylindrical shape, a part ofthe cylindrical shape, a truncated conical shape, and a part of thetruncated conical shape with respect to one axis.